There has been a few posts on dyno numbers of late, and it would seem that most people have no idea at all regarding posted factory horsepower and torque numbers versus reality.

First off factory Hp numbers are taken from the engine while it sits in a jig or stand. The engine is not production, it is always a prototype. This motor is perfect and it is tested under perfect conditions. Honda has a wind tunnel as well thus it has ram air factored into it as well. When you take your lowly production machine to your local shop and have it dynoed you aren't going to see factory numbers. You are without ram air first off and secondly you are testing at the end of the powertrain not the beginning.

Second: Dynos need to be calibrated on a regular basis. Most shops DON'T do this. Calibrating a dyno is expensive and needs to be done by the maker of the dynometer. Shops don't calibrate for another reason as well. Customers want to see high numbers. For some reason Dynos never go out of cal low. They always seem to read higher. I actually had a guy yelling at me one day because his ZX-10R didn't dyno 180 HP like it did at his shop back home. For anybody who doesn't know a ZX-10R is a powerful bike but I've never seen a stock one dyno over 145 HP. Thats quite a difference.

Third: External factors play a roll. As any drag racer will tell you that humidity, temperature, elevation, and air pressure all play a roll in engine operation. Your bike fluctuates its max power quite a bit every day based on these factors. On a dyno you are only getting your engines power for that few minutes.

The dyno is a tool. It measures ball park horsepower and allows tuning shops to gauge whether or not modifications are helping or hurting your power. YES SOME MODS LIKE GP STYLED AND OPEN EXHAUSTS HURT YOUR POWER NOT HELP IT. The numbers you get on a dyno are just an estimate. Don't waste your money going to dyno stock bikes, or bikes with slip-ons. Dyno runs are usually pricey (because dynos are really pricey) and really don't give you an accurate picture.

In closing: Forget about the factory numbers you read in magazines and on the internet. If you take your stock bike into a tuning shop be prepared to be disappointed. Below I'm going to list in my experience what mods add HP and about how much dyno wise.

Slip-on exhaust (they're all pretty much the same) 1-5 HP
Powercommander 1-8 HP (less with internet map)
K&N Filter 0 HP
Synthetic oil 1-1.5 HP
O2 Sensor eliminator (06 and Cali models) 1-1.5 HP

Hopefully this post cleared up some of the myths you have about Dynos and their numbers.

 

Great post.

I've never actually seen any HP numbers that were provided by Honda.

 

i'm assuming the 5HP for slip on is on a liter bike with tuning?

how does an O2 sensor eliminator give more HP?

 

The same way a powercommander does (through the fuel map). Your fuel injection system compensates for the feedback of the oxygen sensor. The oxygen sensor eliminator sends a constant "perfect" signal to the engine. This converts the fuel map into a standard 2 dimensional map (RPM & throttle postion) allowing the bike to run as it was intended without the oxygen sensor trimming the mixture for emissions.

As far as the slipon we had a guy bring us a GSX-R 750 that actually increased about 4.5 HP with a Yosh slip-on (no PC). Usually its about 1-2 HP on a 600, sometimes it actually hurts power (seen that too). That is the highest I've ever seen.

I'm surprised you would question an oxygen sensor before synthetic oil. I figured I'd be explaining that one.

 

Well, since you brought it up what about explaining the synthetic oil one? lol

 

Can you discuss your experience on the Correction factor as well.

Are you using WinPep and what version? Is this a DynoJet or Mustang dyno you are using?

I have ran two dynos, NEVER calibrated with the exception of clearancing a worn truck brake on the drum. We did change the AF meter, but never touched the dyno. It always gave super accurate results when the tach signals were working correctly.

The only time there was a variance in the output (dynoing 300+ RWHP cars) was when our drum brake was sticking.

Mustang vs. Dynojet could explain your numbers vs. the other numbers on this guys 180 HP bike.

When the temp was roughly equal, and correction factor properly used I could dyno a car within 1 RWHP of each other. Not bad.

 

track junkies know about the oil, however negligible it may be...

as for the O2 sensors for bikes and in particular the F4i, it does not work as in a car where the ECU thrives off the O2 signals. when you WOT, the bike works strictly off of whatever map is set to it. the sensor does not tell the ECU to add more fuel to compensate for a lean condition. that's why i question where you picked up the ponies from an O2 eliminator. my experience with them is that they just kill gas mileage as they only serve for fuel efficiency and smog.

 

This post is dead on.. Eliminating the 02 will not add more HP. It adjusts fuel trim, but not during WOT...Same as an automobile..WOT in any vehicle will always ignore the o2.

There is "closed loop" and "open loop" when in closed loop your fuel trims are based on the 02. during "open loop" the ECU doesn't care about the 02...Your bike is in open loop during WOT, during most aggressive acceleration, when the engine is cold, etc...Getting ride of it doesn't help at all.

 

The 02 sensor has an effect on fuel mixture only at 30% and less throttle or less then 4000rpm. This relates to the need to eliminate the 02 sensor if you want to have control in these ranges with a power commander.

I didnt dream this info up. A rep from dynojet is the source.

 

The folks from dynojet informed me that my O2 sensor on my 06 F4i would trim the map settings if it wasn't removed. In trying it on the Dyno they were right. There was a difference between the runs with and without the sensor. Primarily in the lower and low midrange (as you suggested). But there was a fluctuation in the rest of the map as well. I am not a book, nor am I an authority but I feel that I probably have more experience with the dynometer than the average guy out there. I posted some examples of some of the most common mods and what one can expect to see HP wise from them in my experience.

You people are missing the point. We can argue over little stupid bits of HP for the rest of time. I kind of posted those numbers so we could all see the very low HP gains from adding bolt-on stuff to the bike. I was hoping to save people some money by showing them that, without doing serious mods (port, polish, cams etc)to your bike, or having a Powercommander setup you really don't need to pay for dyno runs. They aren't 100% accurate and you are probably going to be dissapointed with the numbers. Everybody zero'ed in to question the HP numbers (from our dynojet dyno which is no doubt not perfect either) and forgot the rest of the post. It was an information post trying to help, there are a thousand threads on this forum concerning bolt-ons and HP gains from them. I wasn't trying to start another one.